Aquatic plants represent a healthy component of a lake’s ecosystem, providing food, habitat and spawning grounds for fish and wildlife, as well as contributing to shoreline protection and overall water quality.

However, the introduction of non-native invasive weeds can have negative effects on lakes and rivers. These plants often outcompete the native species and can degrade water quality, destroy habitat, and spoil or reduce recreation opportunities.

As part of the Spokane River Project License, we have developed the following three Aquatic Weed Management Programs:

Lake Spokane and Nine Mile Reservoir Aquatic Weed Management Program

Coeur d’Alene Lake Aquatic Weed Management Plan for Non-Tribal Waters

Coeur d’Alene Reservation Aquatic Weed Management Plan

The primary elements of these programs include:

Educational programs to inform the public of the problems associated with invasive aquatic weeds and how to prevent their spread and introduction into our water bodies.

Monitor and map the distribution of invasive aquatic weeds within designated areas.

Develop management strategies to help control invasive aquatic weeds.

Avista and its partners are working together to control the following invasive weeds at public and community recreation sites on Lake Spokane: Flowering Rush, Eurasian Water Milfoil, Yellow Floating Heart, White Lily, and Curly-leaf Pondweed.

Avista also monitors for invasive aquatic weeds on Nine Mile Reservoir and will work with its partners to develop a plan to control them if they are found.

In Coeur d’Alene Lake and the lower St. Joe and St. Maries rivers, Avista and its partners are working to control Eurasian Water Milfoil and a hybrid species of milfoil, which are currently the only known invasive aquatic weed species present within the Coeur d’Alene Lake system.

Fish and wildlife habitat due to the creation of non-native monocultures within water bodies and along the shorelines.

Water quality, in which plant sloughing, leaf turnover, and decomposition of large amounts of plant material at the end of the growing season increase phosphorus and nitrogen in the water column. Dense mats of aquatic weeds alter water quality by raising the pH, decreasing oxygen under the mats, and increasing temperature.

Aesthetics by creating monocultures and replacing native vegetation, as well as forming mats of decaying plants along shorelines.

Eurasian Water Milfoil (Myriophyllum spicatum)

Curly-Leaf Pondweed (Potamogeton crispus)

Courtesy of Washington Department of Ecology

White Lily (Nymphaea odorata)

Yellow Floating Heart (Nymphoides peltata)

Courtesy of Washington Department of Ecology

Flowering Rush (Butomus umbellatus)

To help protect our local rivers and lakes from invasive species, here are some tips to remember as you take to the lake or river:

Remove all sediment and vegetation from boats, trailers, and fishing gear when traveling between different lakes or rivers. Don’t forget to clean your waders.

Wash and dry all boats, trailers, and fishing gear thoroughly between trips.

Disinfect gear (especially waders and live wells) if you have been in an area containing aquatic invasive species.

Stop at every boat check station in your area.

Remember, it is illegal to transport invasive species and it only takes one mistake to infest a new area.

Avista holds annual meetings, typically in the winter and spring, to gather input and to provide information about implementing the three aquatic weed management programs. These meetings are essential in that they provide information exchanges that often lead to a more common understanding of the current invasive aquatic weed(s) of concern and how to effectively control these weeds in a cost-effective manner. Avista and its partners have also found that by sharing costs and information they can often accomplish more effective weed control programs with limited resources.